Determination of bopindolol in pharmaceuticals by capillary isotachophoresis

Capillary isotachophoresis (ITP) with conductimetric detection has been used for separating and determining bopindolol (I) in commercial mass-produced pharmaceutical preparations. The optimised operational electrolyte system consisted of 5 mM potassium picolinate and 5 mM picolinic acid (leading electrolyte, LE; pH 5.37) and 10 mM formic acid as the terminating electrolyte (TE). The driving and detection currents were 50 microA (for 350 s) and 10 microA, respectively. The single analysis took about 12 min. Under such conditions the effective mobility of I was determined as 16.73 10(-9)m(2) V(-1) s(-1) (with tetraethylammonium as the mobility standard). The calibration graph relating the ITP zone length to the concentration of I was rectilinear (r=0.99990) in the range 10-100 mg l(-1). The relative standard deviation (R.S.D.) was 0.90% (n=6) when determining 50 mg l(-1) of I in pure test solution. Sample pre-treatment of the tablets involved ice-cooled extraction of I with methanol. The method was suitable for determining I in Sandonorm tablets with R.S.D. value 1.45% (n=6). According to the validation procedure based on the standard addition method the recovery was 97.3%.